/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.client.android;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;

import androidx.appcompat.app.AppCompatActivity;


/**
 * An HTML-based help screen with Back and Done buttons at the bottom.
 *
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class HelpActivity extends AppCompatActivity {

    // Use this key and one of the values below when launching this activity via intent. If not
    // present, the default page will be loaded.
    public static final String REQUESTED_PAGE_KEY = "requested_page_key";
    public static final String DEFAULT_PAGE = "index.html";
    public static final String WHATS_NEW_PAGE = "whatsnew.html";

    private static final String BASE_URL =
            "file:///android_asset/html-" + LocaleManager.getTranslatedAssetLanguage() + '/';
    private static final String WEBVIEW_STATE_PRESENT = "webview_state_present";

    private WebView webView;
    private Button backButton;

    private final Button.OnClickListener backListener = new Button.OnClickListener() {
        @Override
        public void onClick(View view) {
            webView.goBack();
        }
    };

    private final Button.OnClickListener doneListener = new Button.OnClickListener() {
        @Override
        public void onClick(View view) {
            finish();
        }
    };

    @Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.help);

        webView = (WebView) findViewById(R.id.help_contents);
        webView.setWebViewClient(new HelpClient());

        // Froyo has a bug with calling onCreate() twice in a row, which causes the What's New page
        // that's auto-loaded on first run to appear blank. As a workaround we only call restoreState()
        // if a valid URL was loaded at the time the previous activity was torn down.
        Intent intent = getIntent();
        if (icicle != null && icicle.getBoolean(WEBVIEW_STATE_PRESENT, false)) {
            webView.restoreState(icicle);
        } else if (intent != null) {
            String page = intent.getStringExtra(REQUESTED_PAGE_KEY);
            if (page != null && page.length() > 0) {
                webView.loadUrl(BASE_URL + page);
            } else {
                webView.loadUrl(BASE_URL + DEFAULT_PAGE);
            }
        } else {
            webView.loadUrl(BASE_URL + DEFAULT_PAGE);
        }

        backButton = (Button) findViewById(R.id.back_button);
        backButton.setOnClickListener(backListener);
        View doneButton = findViewById(R.id.done_button);
        doneButton.setOnClickListener(doneListener);
    }

    @Override
    protected void onSaveInstanceState(Bundle state) {
        String url = webView.getUrl();
        if (url != null && url.length() > 0) {
            webView.saveState(state);
            state.putBoolean(WEBVIEW_STATE_PRESENT, true);
        }
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            if (webView.canGoBack()) {
                webView.goBack();
                return true;
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    private final class HelpClient extends WebViewClient {
        @Override
        public void onPageFinished(WebView view, String url) {
            setTitle(view.getTitle());
            backButton.setEnabled(view.canGoBack());
        }

        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (url.startsWith("file")) {
                // Keep local assets in this WebView.
                return false;
            } else {
                // Open external URLs in Browser.
                startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
                return true;
            }
        }
    }
}
